I just bought a Dell SP2309W 2048 x 1152 resolution and I'm really confused in which Adapter I should buy this one or the Mini Displayport to DVI?

I'm really confused because I heard that the Mini Displayport to DVI adapter resolution only goes up to 1920 x 1200 max but my monitor's resolution is 2048 x 1152 so that won't work. And I was thinking to buy the Mini Displayport to dual-Link DVI Adapter but I herd it doesn't work with other monitors only the 30inch Apple Cinema Display and its way to much for an adapter. So what could I do im stuck is there anything I could do?

Yes. Displayport is a standard which allows the computer to determine what is connected to the other end: either a DVI computer monitor OR an HDMI device such as an HDTV. Just take your monitor to an apple store and your mac and they will get you setup. As far as I know you have to use the apple adapter as the plug is a different size than the Display port plugs for PC's.